Updated Constraints on Asteroid-Mass Primordial Black Holes as Dark Matter

Understand

Microlensing of stars places significant constraints on sub-planetary-mass compact objects, including primordial black holes, as dark matter candidates.

• As the lens' Einstein radius in the source plane becomes comparable to the size of the light source, however, source amplification is strongly suppressed, making it challenging to constrain lenses with a mass at or below $10^{-10}$ solar masses, i.e.
• asteroid-mass objects.
• Current constraints, using Subaru HSC observations of M31, assume a fixed source size of one solar radius.